Process of producing silicon.



UNITED STATES PATENT OFFICE.

FRANK J. TONE, OF NIAGARA FALLS, NEW YORK, ASSIGNOR TO THE CARBORUNDUM COM- PANY, OF NIAGARA FALLS, NEW YORK, A CORPORATION OF PENNSYLVANIA.

PROCESS OF PRODUCING- SILICON.

Specification 0! Letters Patent.

Patented Dec. 8, 1908.

To all whom'it may concern:

Be it known thatlI, FRANK J. TONE, of Niagara Falls, Niagara county, New York, have invented a new and useful Process of Producing Silicon, of which the following is a full, clear, and exact description.

This invention refers to improvements in the manufacture of silicon from silicates of aluminum and has for its object the production therefrom of new and useful substances containing silicon or aluminum or both of these elements. I

' Aluminum silicate is an ore of aluminum of wide occurrence and is the basis of all true clays. I have'discovered that by smelting this ore in the electric furnace together with carbon as a reducin agent, it is possible to obtain therefrom e emental silicon in metallic form and alumina in a fused crystalline form havin great hardness and abrasive qualities an possessing high purit making it useful in various arts idwhicfi alumina is employed.

I take kaolin which is the urest form of aluminum silicate preferably rst calcining it 7 to free it from the combined water, and mix therewith a suitable reducing agent such asv carbon, usin 222 parts of the ore to 48 arts of carbon, 9. though I do not wish to imit myself to these exact proportions. When this charge is smelted in the electric furnace,

a reaction occurs in accord ance with the -fol-.

lowing equation:

A1,O,.2SiO' 4Q= A1 0 2Si+ 4C0.

The aluminum silicate is dissociated and the silicon therein is reduced to its elemental form. There being insufficient carbon to also reduce the aluminum, this does not part with its oxygen and appears in the form of fused oxid of aluminum. The silicon gathers in masses through the fused alumina, the extent of the ag lomeration depending upon the size of the I urnace, the temperature and other conditions. The fused alumina is of considerably hi her specific gravity than the silicon and ten s to settle torthe bottom of the furnace.

Any form of electric arc furnace of the vertical. depending electrode type is suitable for carrying out this rocess. he charge mix ture is fed into t e crucible of the furnace around the are where it fuses and is reduced as above described. The fused mass builds ulpas the electrodes are raised and as more 0 arge is added from time to time until there is formed an ingot of considerable size. After a sufiicient amount of ore has been smelted to form an ingot of a convenient size to handle, the fused material is allowed to cool and is .broken up and the silicon separated from the alumina. This separation may be done in various ways. A rough separation may be made by hand after which I prefer to crush the finished productand separate the grains of alumina from silicon by concentration. When working on a large scale, it may be found desirable to tap out one or both productsin molten form.

Silicon obtained by this process is useful for various purposes such as the refining of iron, steel and copper, and as a reducing agent in the reduction of refractory ores. The alumina is useful as an abrasive and also as an ore for the I production of metallic aluminum.

I claim 1. The method of reducing silicon from ores containing aluminum and silicon, which consists in forming a mixture of the ore and carbon sufiiciefit to reduce the silicon to its elementary form and insufficient to reduce the aluminum, said mixture being substantially free from iron-containing and basic metalliferous materials, subjecting this mixture to electrically'developed heat sufficient to reduce the silicon and to fuse the alumina,

and then separating the elemental silicon fromfthe fused alumina.

2. The method of reducing aluminum sili-. cate, which consists in forming a mixture of .aluminum silicate and carbon sufiicient to reduce the silicon to its elementary form, and

insufficient to reduce the aluminum, said mixture being substantially free from ironcontaining and basic metalliferous materials, subjecting this mixture to electrically develo'ped'heat sufficient to reduce the silicon and to fuse the alumina, and then separating the elemental silicon from the alumina.

In testimony whereof, I have hereunto set my hand.

I FRANK J. TONE. Witnesses:

.GnA LEs OHORMANN, S; S: Dmmnn. 

